4 Replies Latest reply on Oct 7, 2014 7:32 PM by Pablo Jorge

    How can I simplify a repetitive piece?

    Pablo Jorge

      I want to analisy the contact between two tooth in a gear theet.

       

      Well,  I really need to analize the contact in the 6 tooth that are really working, but I don't wont to spend memory and CPU meshing all the gear theet just to see they have no stress.

       

      In other words, is it possible to  " cut" the piece and reduce the analisys only to the interesting part, inside the red line?

       

      Of course, I don't want to make two new drawings.

       

      engranajes.jpg

        • Re: How can I simplify a repetitive piece?
          Shaun Densberger

          It really depends on what you're interested in solving for and how you want to use the results. There are three ways you could do this analysis:

          1. Meshing each gear in its entirety with 3D solid elements.
          2. Meshing each gear in its entirety with 2D plane stress elements.
          3. Cutting out a portion of each gear and meshing it with either 2D plane stress or 3D elements.

          If the thickness of the gears is relatively small compared to the other dimensions (think of a cog on a bicycle), then a 2D Plane Stress assumption is good. If the gear is relatively thick compared to the other dimensions, then 3D will be more appropriate. How thick are the gears?

           

          Cutting out a portion of each gear is, technically speaking, not correct; the constraints that you'd add on the cut surfaces to prevent theta rotation will result in a model that is stiffer. This increased stiffness is probably not too big of an issue (if your cut planes are far enough away from the gear teeth you're interested in), but the only real way to quantify the difference would be to solve both. Cutting in the red lined area would be (in my opinion) way too close; I'd suggest cutting out a wedge of each gear that is about 90 degs.

          • Re: How can I simplify a repetitive piece?
            Jared Conway

            agree with shaun here, i don't see any way to leverage symmetry or cyclic symmetry or submodeling in anyway. best to go with 2d. but if you have elements that aren't being stressed, why not just make the mesh over there really coarse?